Euro Cave

ALH_4

Viessmann's data is somewhat conservative. It's amazing what a little control does for you with your heating system. It's for this reason I refuse to sell a boiler without an outdoor reset control. If nothing else it gives a lot more control than an aquatat and a relay can.

It's sort of fun to experiment with a heating system to try an doptimize its performance. Many homeowners don't realize how interesting they are until they have one.

-Andrew

Mike T., Swampeast MO

This heating season looks to be most interesting.

Will have fairly crude solar diversity installed on the Vitodens. Don't want to do the full-blown system until I'm certain that the fairly crude works...

Am going to operate the boiler in what Mark Etherton so nicely names the "Euro Cave Mode".

Original gravity system with greatly oversized standing iron with TRVs. Found last year that I could significantly reduce the supply temp without reducing measured room but...BUT found that my comfort suffered while doing the sedentary computer work that takes up about half my time.

No problem at least when doing real labor of renovation...

Will still use my 0.8 reset ratio but will reduce shift to zero. In other words, supply temp will be about 115 degrees at 5 degrees outside. I realize that reset curve is rather common for radiant systems with a highly conductive heat transfer mechanism, but for iron radiators????

My "wild" radiant floors are certain to suffer as even the copper in T-fin under 3/4" plywood can't manage at these temps. At least I have supplemental electric B/B heat in the exposed hydronic radiant bath...

Calculations tell me that I'll exceed the flow capacity of the built-in circulator. (No low-loss header, no other circulator.) BUT, I was utterly shocked when I was able to significantly and rapidly raise the temp in the entire house last year in fairly cold weather. My calculations told me then that there was NO WAY that the highest, farthest (and largest) rad in the house would heat in such conditions. I fully expected the nearest, lowest rads with 1 1/4" TRVs to "hog" the flow.

While comfort is certain to suffer, I'm trying to keep my total heating cost at or below last year. Another 25% reduction??? (Hopefully the radiant bath floors won't feel cold to the bare foot, but I have my doubts...)

Will post some operational graphs as soon as I can make some sense and compare with last year. Seriously doubt that the boiler will be used before late November.

Constantin

Hear Hear!

Andrew,
You're absolutely right... and that's why I went down to Viessmann to learn about the Vitotronic 200. What a great match for the Vitola in our home. After the class, I typed up a two-page single-space settings manual so I can quickly reference all the settings that are open for me to change. Once I started making changes to the Vitotronic, I realized how little my boiler had been adjusted beforehand.

Some day, I hope I will be able to change address 02 to a value different than 0. Time will tell.

In the meantime, I hope that Viessmann will come up with a way for contractors to more quickly make changes to the settings in their boilers. I'm hoping for some easy-to-implement solution like a USB memory card that can be programmed with a computer (via a interactive decision-tree computer program) and then inserted into the boiler to transfer the settings.

Mike T., Swampeast MO

And a nice thing about their control theory is that the USER is given free and easy access to the reset curve.

That little variable speed circulator continues to amaze me.

ALH_4

Slope & Shift

The difficult part for the installing contractor is that he/she cannot foresee how the home will behave under differing circumstances. Every home behaves a little differently, and every home owner uses their home differently. It does take a little effort for the home owner to learn how to fine tune the system, but there are real benefits. Even just a slope dial next to the shift dial would be handy for fine tuning.

Mike, you have proven with real empirical data, and anecdotal evidence just how well modulating, condensing boilers can work. We all owe you for the time you have taken to show us how the Vitodens has behaved in your application, which is not a rare one. I, for one, have learned from what you have done.

-Andrew

Mike T., Swampeast MO

Not sure that you'd want a slope dial so easily accessible. Slope seems quite highly related to the structure and the nature of the heat emitters and small changes can have profound affect.

Viessmann told me that the Vitodens is often run WAY too hot in the US. Am going to really test that theory this year. 139° @ 8° outside for a standing iron system didn't seem "way too hot" to me, but guess I'll find out.

Do wish that my radiation had better sizing balance, but I'm pretty much stuck with what the dead men did.

Ron Schroeder_3

Gentlemen, don't forget

to show the homeowner how to use the little rotary encoders marked with sun and moon symbols. These controls make small changes compared to what changing the slope and shift does. They also do not require any manipulation of buttons...